Programmable plug system and method for controlling formation access in multistage hydraulic fracturing of oil and gas wells

ABSTRACT

Programmable plug system for accessing and isolating formations during hydraulic fracturing, consisting of a Programmable Plug and plurality of Sliding Sleeve Valves installed in the casing string of a wellbore wherein Programmable Plug travels down the casing string, through the casing and Sliding Sleeve Valves wherein during its passage the Programmable Plug recognizes and counts each sleeve using on-board sensors, electronics and software and wherein the Programmable Plug utilizes recognition information to locate, activate and set itself into the Sliding Sleeve Valve according to programmed sequence stored in the on-board memory wherein this activation and setting of the Programmable Plug forms physical coupling between Programmable Plug and allows the Programmable Plug to engage and actuate the Sliding Sleeve and wherein applying the pressure from the surface causes opening of the Sliding Sleeve Valve, wherein this opening provides access to the zone adjacent to the Sliding Sleeve Valve while sealing and isolating the zones below the Sliding Sleeve Valve and wherein applying the pressure in the opposite direction, or pulling on the winch attached to the Programmable Plug causes the Programmable Plug to unset itself and travel up the casing string towards the next Sliding Sleeve Valve where setting, actuation, and opening is repeated for that Sliding Sleeve Valve.

BACKGROUND OF THE INVENTION

In the Oil and Gas industry, multistage fracturing operations have been developed to increase production from low permeability production zones, particularly from shale zones. In multistage fracturing operations the desire is to perform fracturing in designated zones. Wells are drilled and completed prior to hydraulic fracturing and in order for fracturing to occur access to formation needs to be achieved. Currently there are two methods of accessing the well formation for hydraulic fracturing. First one is by using plugs and perforations where well casing is perforated using explosive charges, and perforated zones are sealed and isolated using plugs. With second method, casing string is equipped with a number of valves placed along pay zones according to pre-determined arrangement, these valves are can be opened or closed to control zone access. Casing string equipped with valves provides more flexibility during fracturing operations and also later during well production. There are a number of valves and plug systems in use today, many of them described in patents:

U.S. Pat. No. 3,054,415—Sleeve valve apparatus

U.S. Pat. No. 4,520,870—Well flow control device

U.S. Pat. No. 4,893,678—Multiple-set downhole tool and method

U.S. Pat. No. 5,263,683—Sliding sleeve valve

U.S. Pat. No. 6,189,619—Sliding sleeve assembly for subsurface flow control

U.S. Pat. No. 6,597,175—Electromagnetic Detector Apparatus

U.S. Pat. No. 6,776,239—Tubing Conveyed Fracturing Tool and Method

U.S. Pat. No. 7,363,967—Downhole Tool with Navigation System

U.S. Pat. No. 9,010,447—SLIDING SLEEVE SUB AND METHOD

U.S. Pat. No. 9,752,409—MULTISTAGE FRACTURING SYSTEM WITH Electronic Counting System

US20110278017A1—Sliding sleeve sub and method and apparatus for wellbore fluid treatment

US20120097398A1—Multi-Zone Fracturing System

US20150247375A1—Frac Plug

US20160097269A1—Smart Frac Plug System and Method

US20170234108A1—Frac Plug and Methods of Use

SUMMARY OF INVENTION

Programmable plug system comprises of Programmable Plug and plurality of Sliding Sleeve Valves inserted into the wellbore casing string at specific depths determined by wellbore design.

Certain embodiments of the invention herein pertain to a system consisting of a Programmable Plug assembly and plurality of Sliding Sleeve Valve assemblies wherein the Programmable Plug assembly consists of housing, seals, mechanical dogs, sensors, batteries, microprocessor, memory and one or many electric actuators wherein each Sliding Sleeve Valve includes one or many distinct shape features detectable via said Programmable Plug sensors and wherein the microprocessor processes the results of such detection and determines the presence of said Programmable Plug assembly within said Sliding Sleeve Valve and wherein the microprocessor determines the direction of movement of Programmable Plug assembly in reference to said Sliding Sleeve Valve and wherein the microprocessor updates the count of Sliding Sleeve Valve encountered by the Programmable Plug assembly as it travels up or down the casing and wherein the microprocessor relates the Sliding Sleeve Valve number with the pre-programmed number stored in memory and wherein the microprocessor activates the actuator and sets the Programmable Plug assembly once Programmable Plug assembly arrives precisely within the interior of a Sliding Sleeve Valve matching the pre-programmed number and wherein the mechanical coupling is achieved between Programmable Plug and Sliding Sleeve Valve and wherein the pumping pressure from the surface moves the Programmable Plug assembly together with a coupled part of the Sliding Sleeve Valve resulting in opening of the Sliding Sleeve Valve and providing access to the zone adjacent to the Sliding Sleeve Valve while simultaneously providing a seal and isolating the section of the well bore section below said Sliding Sleeve Valve.

In certain other embodiments of the invention, surface mounted slick line or wire line winch is connected with solid steel cable to the rear end of Programmable Plug assembly wherein the winch is allowed to unwind as Programmable Plug assembly travels down the casing and wherein the winch is actuated at the surface to pull the Programmable Plug assembly in order to transport the Programmable Plug assembly to the next Sliding Sleeve Valve or to pull the Programmable Plug assembly completely out of the casing.

In certain other embodiments of the invention the memory is preprogrammed with a number of a target Sliding Sleeve Plug that needs to be closed, wherein the Programmable Plug assembly is suspended on a surface mounted winch with solid steel cable wherein the Programmable Plug assembly counts Sliding Sleeve valves as it travels down the casing and wherein the Programmable Plug activates and engages the target Sliding Sleeve Plug allowing the closing of said Sliding Sleeve valve by pulling on the steel cable attached to Programmable Plug assembly.

In certain other embodiments of the invention plurality of proximity switches are installed into the sensor head of Programmable plug assembly wherein proximity switches are arranged in a radial configuration perpendicular to the longitudinal axis and wherein the Sliding Sleeve Valve is designed with a section of smaller diameter such that all proximity switches are activated upon passage of Programmable Plug assembly through said section of smaller diameter of the Sliding Sleeve Valve.

In certain other embodiments of the invention plurality of mechanical spring loaded pins are installed into the sensor head wherein said pins are allowed to retract upon mechanical contact with the smaller radius section of the Sliding Sleeve Valve wherein this simultaneous retraction of said pins is detected using one or many optical, ultrasonic or force sensors installed in the interior of the sensor head.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a section view a Sliding Sleeve Valve in the casing string and Programmable Plug activated in the Sliding Sleeve Valve.

FIG. 1a shows the Sliding Sleeve Valve in closed position.

FIG. 1b shows the Sliding Sleeve Valve in open position

FIG. 2 is a view of Programmable Plug assembly

FIG. 2a shows Programmable Plug assembly with mechanical dogs retracted

FIG. 2b shows Programmable Plug assembly with mechanical dogs extended

FIG. 3 is a section view of a Programmable Plug assembly

FIG. 4 is a section view of Sliding Sleeve valve

FIG. 4a shows Sliding Sleeve Valve in closed position

FIG. 4b shows Sliding Sleeve Valve in open position

FIG. 5 is a section view of Programmable Plug assembly showing different configurations of sensors

FIG. 5a shows coils wound on the outer surface in longitudinal direction configuration

FIG. 5b shows detection coils arranged in radial direction configuration

FIG. 5c shows sensor head with mechanical pins

DESCRIPTION OF THE INVENTION

Programmable Plug System comprises of Programmable Plug assembly (FIG. 1, Item 1) and plurality of Sliding Sleeve Valves (FIG. 1, Item 2) inserted into the casing string (FIG. 1, Item 3). Programmable Plug consists of three tubular sections integrated into one assembly. First tubular section (FIG. 2, Item 21) contains two sets of proximity switches (FIG. 3, Item 37) positioned apart in the tubular axial direction. Each set of proximity switches contains plurality of proximity switches arranged in radial direction around tubular axis. Sensitivity of said proximity switches is adjusted such that they can only be activated at a known predefined distance. Some proximity switches are allowed to activate while Programmable Plug moves through the casing however passing through the distinct small diameter (FIG. 4, Item 42) of the Sliding Sleeve Valve activates all the switches and allows the Programmable Plug to detect the passage through the Sliding Sleeve Valve. Movement direction is determined from the order of activation of said sets of proximity switches. Outputs of said proximity switches are connected to the on-board microprocessor where on-board software records the direction and calculates the number of Sliding Sleeve Valve that is being traversed. Microprocessor compares said Sliding Sleeve Valve number with the current sequence number preprogrammed in the memory and it activates the electro-mechanical dogs (FIG. 2, Item 24) that set the Programmable Plug assembly into the Sliding Sleeve Valve. In another embodiment of the invention, Sensor Section (FIG. 5a , Item 51) contains two coils (FIG. 5a , Item 52) wound in circular groves on the outer surface of the first tubular section positioned apart in the longitudinal axis direction. Said coils respond to the change in internal diameter of the casing and the Sliding Sleeve Valve determining plug movement direction, number of sleeve passed and activate electro-mechanical latches to set the plug into the Sliding Sleeve Valve. Another embodiment of the Sensors Section (FIG. 5b , Item 53) comprises two or more sets of coils (FIG. 5b , Item 54) positioned apart in the axial direction. Each set of coils consists of plurality of individual coils with coil axis arranged in radial direction around longitudinal tubular body axis. One of the side surfaces of the coils are flush with tubular body outer surface or offset from surface inward or outward. In certain other embodiments of the invention plurality of mechanical spring loaded pins (FIG. 5c , Item 56) are installed into the sensor head (FIG. 5c , Item 55) wherein said pins are allowed to retract upon mechanical contact with the smaller radius section of the Sliding Sleeve Valve where in this retraction of said pins is detected using one or many optical, ultrasonic or force sensors installed in the interior of the sensor head.

Second tubular section (Electro-Mechanical Section) (FIG. 2, Item 22) contains microprocessor, memory, batteries (FIG. 3, Item 36), electric motor (FIG. 3, Item 35), screw shaft (FIG. 3, Item 32), tube with internal thread (FIG. 3, Item 31) coupled to thread on screw shaft. Screw shaft is constrained by bearing (FIG. 3, Item 34) inside the Second Tubular section. It is connected to and driven by electric motor (FIG. 3, Item 35). Internally threaded tube is driven by screw shaft in axial direction both ways.

Third tubular section (Dogs and Seal Section) (FIG. 2, Item 23), contains dogs (FIG. 2, Item 24) that lock into the particular Sliding Sleeve Valve that has to open or close, and seal (packer) (FIG. 2, Item 25) that insulates spaces above and below the plug allowing the fracturing flow to penetrate the zone through the openings on the Sliding Sleeve Valve. Dogs are activated by wedge shaft (FIG. 3, Item 30) connected to the internally threaded tube.

Plurality of Sliding Sleeve Valves is installed in the casing string at specific depths determined by wellbore design. Sliding Sleeve Valve consists of outer tubular body (Sliding Sleeve Valve Body) (FIG. 4, Item 41) with holes or slots circularly arranged around longitudinal axis of tubular body, and Sliding Sleeve (FIG. 4, Item 42) with seals between outer tubular body and sleeve itself insulating holes or slots from pressure inside of the casing string. Sliding Sleeve has the internal diameter smaller than the casing internal diameter, allowing the Programmable Plug Sensors to recognize the change in internal diameters, count the Sliding Sleeve Valve and lock itself into the Sliding Sleeve with dogs when activated.

Programmable Plug may be used as standalone unit wherein it is pumped down hole and moved up hole by well pressure. Optionally, Programmable Plug may be used with wire line or slick line winch for convenience and enhanced operations. Standard wire line/ slick line connection is part of the Programmable Plug (FIG. 3, Item 38). 

We claim:
 1. Programmable Plug System for controlling formation access in multi stage hydraulic fracturing of oil & gas wells comprising: a. Programmable Plug b. Plurality of Sliding Sleeve Valves featuring specific internal diameter detectable by Programmable Plug sensors c. Instrumented slick line or wire line winch
 2. Programmable Plug of claim 1 comprising: a. Sensors Section b. Electro-Mechanical Section c. Dogs and Seal Section
 3. Sensors Section of claim 2 comprising: a. Tubular body b. At least one battery powered sensor capable of detecting a change of internal diameter of the tubular traversed by the plug c. At least one battery powered sensor capable of detecting the direction of movement of the Programmable Plug
 4. Sensors Section of claim 2 comprising: a. Tubular body b. One, two or more sets of proximity switches positioned apart in the axial direction wherein each set is comprising of plurality of proximity switches arranged in radial direction around longitudinal axis of the plug with the sensing face facing the outer surface of the tubular body wherein said face is flush with the outer surface or offset a certain distance wherein the switches are activated by the change in diameter between casing and Sliding Sleeve being traversed.
 5. Sensors Section of claim 2 comprising: a. Tubular body b. One, two or more sets of coils positioned apart for the given distance in the axial direction wherein each coil is wound into circular groves on the outer surface of the tubular body positioned apart in the longitudinal plug axis direction wherein the outer cylindrical surface of the coil is flush with the tubular body outer surface or offset from it a certain distance and wherein said coils detect the change in diameter between casing and the Sliding Sleeve being traversed.
 6. Sensors Section of claim 2 comprising: a. Tubular body b. One, two or more sets of coils positioned apart in the axial direction wherein each set of coils consists of plurality of individual coils with coil axis arranged in radial direction around longitudinal axis wherein one of the side surfaces of the coils is flush with outer surface of tubular body or is offset from said surface for the certain distance inward or outward and wherein said coils detect the change in diameter between casing and Sliding Sleeve Valve.
 7. Sensors Section of claim 2 comprising: a. Tubular body b. One or more sets of spring loaded pins wherein said pins are allowed to retract upon mechanical contact with the smaller diameter section of the Sliding Sleeve valve wherein this retraction of said pins is detected using one or many optical, ultrasonic, proximity or force sensors installed in the sensors head.
 8. Electro-mechanical Section of claim 2 comprising; a. Tubular body with sealed inner cavity b. Battery operated microprocessor or microcontroller connected to one or many sensors programmed to periodically read sensors and record the presence of Sliding Sleeve Valve, record the current number of the Sliding Sleeve Valve being traversed and compare it against the current sequence number and record time c. Battery powered memory storing pre-programmed sequence of Sliding Sleeve numbers that need to be actuated d. Batteries e. Battery powered electric actuator
 9. Dogs and Seal Section of claim 2 comprising: a. Tubular body b. Dogs to engage and lock into the Sliding Sleeve Valve c. Seal to seal against Sliding Sleeve Valve and insulate pressure below the Programmable Plug from the larger pressure above it d. Axially moving shaft to activate and deactivate dogs coupled with electric actuator e. Wire-line or slick-line connection
 10. Sliding Sleeve Valve of claim 1 comprising: a. Outer tubular body with threads to fit in the casing string b. Circularly arranged holes placed around tubular body axis providing fluid communication between inside and outside of the tubular body c. Inner tubular body which fits into the outer tubular body and seals holes in the outer tubular body. Inner tubular body is axially moved by the Programmable Plug of claim 2 along the tubular body axis wherein it opens or closes holes in the outer tubular body d. Inner tubular body with a specific inner diameter allowing the Programmable Plug of claim 2 to detect and count the Sliding Sleeves Valve, latch into it and seal it.
 11. Instrumented steel wire winch of claim 1 comprising: a. Coil of steel wire terminated with a connector to connect to the Programmable Plug of claim 2 b. Actuator for turning the coil and pulling the Programmable Plug c. Electronic encoder for measuring slick line/wire line movement. d. Slick line/wire line tension-meter e. Timer synchronized with time recorded by a microprocessor and microcontroller of claim 8b
 12. Method for controlling formation access in multistage hydraulic fracturing of Oil and Gas wells, the method comprising steps of: a. Installing of Sliding Sleeve Valves at designated depths b. Programming the sequence of Sliding Sleeve Valve numbers into the memory of Programmable Plug wherein the Sliding Sleeve Valve number corresponds to its position in the casing counted from the top of the well wherein the Sliding Sleeve Valve at the smallest depth is marked as the first and wherein its number is designated as one c. Disposing Programmable Plug into the casing of a wellbore d. Pumping the fluids into the casing e. Causing the Programmable Plug to travel inside the casing towards the bottom of the well f. Monitoring sensor signals and detecting the passage of Programmable Plug through Sliding Sleeve Valve g. Increasing the current Sliding Sleeve Valve number each time the Programmable Plug detects the passage through the Sliding Sleeve Valve in downward direction h. Comparing the current Sliding Sleeve Valve number with the current sequence number stored in memory i. Activating the dogs and setting the Programmable Plug into the Sliding Sleeve Valve when current Sliding Sleeve Valve number is equal to the current sequence number j. Confirming the Programmable Plug was set and Sliding Sleeve Valve was open by correlating pressure reading from the pumps k. Selecting the next number from the sequence stored in memory l. Allowing the Programmable Plug to move up the casing m. Decreasing the current Sliding Sleeve Valve number each time the Programmable Plug detects the passage through the Sliding Sleeve Valve in upward direction n. Confirming the setting of the Programmable Plug using winch rotary encoder and tension sensor o. Pulling the Programmable Plug out of the casing with the wire line or slick line winch We claim:
 1. Programmable Plug System for controlling formation access in multi stage hydraulic fracturing of oil & gas wells comprising: a. Programmable Plug b. Plurality of Sliding Sleeve Valves featuring specific internal diameter detectable by Programmable Plug sensors c. Instrumented slick line or wire line winch
 2. Programmable Plug of claim 1 comprising: a. Sensors Section b. Electro-Mechanical Section c. Dogs and Seal Section
 3. Sensors Section of claim 2 comprising: a. Tubular body b. At least one battery powered sensor capable of detecting a change of internal diameter of the tubular traversed by the plug c. At least one battery powered sensor capable of detecting the direction of movement of the Programmable Plug
 4. Sensors Section of claim 2 comprising: a. Tubular body b. One, two or more sets of proximity switches positioned apart in the axial direction wherein each set is comprising of plurality of proximity switches arranged in radial direction around longitudinal axis of the plug with the sensing face facing the outer surface of the tubular body wherein said face is flush with the outer surface or offset a certain distance wherein the switches are activated by the change in diameter between casing and Sliding Sleeve being traversed.
 5. Sensors Section of claim 2 comprising: a. Tubular body b. One, two or more sets of coils positioned apart for the given distance in the axial direction wherein each coil is wound into circular groves on the outer surface of the tubular body positioned apart in the longitudinal plug axis direction wherein the outer cylindrical surface of the coil is flush with the tubular body outer surface or offset from it a certain distance and wherein said coils detect the change in diameter between casing and the Sliding Sleeve being traversed.
 6. Sensors Section of claim 2 comprising: a. Tubular body b. One, two or more sets of coils positioned apart in the axial direction wherein each set of coils consists of plurality of individual coils with coil axis arranged in radial direction around longitudinal axis wherein one of the side surfaces of the coils is flush with outer surface of tubular body or is offset from said surface for the certain distance inward or outward and wherein said coils detect the change in diameter between casing and Sliding Sleeve Valve.
 7. Sensors Section of claim 2 comprising: a. Tubular body b. One or more sets of spring loaded pins wherein said pins are allowed to retract upon mechanical contact with the smaller diameter section of the Sliding Sleeve valve wherein this retraction of said pins is detected using one or many optical, ultrasonic, proximity or force sensors installed in the sensors head.
 8. Electro-mechanical Section of claim 2 comprising; a. Tubular body with sealed inner cavity b. Battery operated microprocessor or microcontroller connected to one or many sensors programmed to periodically read sensors and record the presence of Sliding Sleeve Valve, record the current number of the Sliding Sleeve Valve being traversed and compare it against the current sequence number and record time c. Battery powered memory storing pre-programmed sequence of Sliding Sleeve numbers that need to be actuated d. Batteries e. Battery powered electric actuator
 9. Dogs and Seal Section of claim 2 comprising: a. Tubular body b. Dogs to engage and lock into the Sliding Sleeve Valve c. Seal to seal against Sliding Sleeve Valve and insulate pressure below the Programmable Plug from the larger pressure above it d. Axially moving shaft to activate and deactivate dogs coupled with electric actuator e. Wire-line or slick-line connection
 10. Sliding Sleeve Valve of claim 1 comprising: a. Outer tubular body with threads to fit in the casing string b. Circularly arranged holes placed around tubular body axis providing fluid communication between inside and outside of the tubular body c. Inner tubular body which fits into the outer tubular body and seals holes in the outer tubular body. Inner tubular body is axially moved by the Programmable Plug of claim 2 along the tubular body axis wherein it opens or closes holes in the outer tubular body d. Inner tubular body with a specific inner diameter allowing the Programmable Plug of claim 2 to detect and count the Sliding Sleeves Valve, latch into it and seal it.
 11. Instrumented steel wire winch of claim 1 comprising: a. Coil of steel wire terminated with a connector to connect to the Programmable Plug of claim 2 b. Actuator for turning the coil and pulling the Programmable Plug c. Electronic encoder for measuring slick line/wire line movement. d. Slick line/wire line tension-meter e. Timer synchronized with time recorded by a microprocessor and microcontroller of claim 8b
 12. Method for controlling formation access in multistage hydraulic fracturing of Oil and Gas wells, the method comprising steps of: a. Installing of Sliding Sleeve Valves at designated depths b. Programming the sequence of Sliding Sleeve Valve numbers into the memory of Programmable Plug wherein the Sliding Sleeve Valve number corresponds to its position in the casing counted from the top of the well wherein the Sliding Sleeve Valve at the smallest depth is marked as the first and wherein its number is designated as one c. Disposing Programmable Plug into the casing of a wellbore d. Pumping the fluids into the casing e. Causing the Programmable Plug to travel inside the casing towards the bottom of the well f. Monitoring sensor signals and detecting the passage of Programmable Plug through Sliding Sleeve Valve g. Increasing the current Sliding Sleeve Valve number each time the Programmable Plug detects the passage through the Sliding Sleeve Valve in downward direction h. Comparing the current Sliding Sleeve Valve number with the current sequence number stored in memory i. Activating the dogs and setting the Programmable Plug into the Sliding Sleeve Valve when current Sliding Sleeve Valve number is equal to the current sequence number j. Confirming the Programmable Plug was set and Sliding Sleeve Valve was open by correlating pressure reading from the pumps k. Selecting the next number from the sequence stored in memory l. Allowing the Programmable Plug to move up the casing m. Decreasing the current Sliding Sleeve Valve number each time the Programmable Plug detects the passage through the Sliding Sleeve Valve in upward direction n. Confirming the setting of the Programmable Plug using winch rotary encoder and tension sensor o. Pulling the Programmable Plug out of the casing with the wire line or slick line winch 